Using the book, Field Manual for Water Quality Monitoring, the National Sanitation Foundation surveyed 142 people, representing a wide range of positions at the local, state, and national level, about 35 water quality tests for possible inclusion in an index. Nine factors were chosen and some were judged more important than others, so a weighted mean is used to combine the values.
So that field measurements could be converted to index values, respondents were asked by questionnaire to graph the level of water quality (0 through 100) corresponding to the field measurements (e.g., pH 2-12). The curves were then averaged and are thought to represent the best professional judgment at this time.
The Water Quality Index Calculator below allows you to enter the latitude and longitude for your site or to pick your location from the Google Earth Map. The calculator completes the individual and group calculation and permits you to generate a customized report.
The Water Quality Index Calculator has two modes - Actual and Training. Actual is meant for real-world testing of actual sites; Training mode is used for educational simulations. If you choose actual, your data will be contributed to our Citizen Science Global Water Quality Database & Map that we will be making available as a shared public resource.